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References Cited:
The field of this invention is that of occupant propelled vehicles (class 280/200), propelled by hand (class 280/242.1), by means of a lever connected to a crank (class 280/247), wherein the vehicle is constructed to be steered by the seat of the vehicle under influence of the body of the occupant (class 280/235). The vehicle disclosed herein is intended for, but not limited to, the outdoor leisure use of persons with restricted or no capacity of the lower limbs.
Beyond the common wheelchair, there has opened up in recent years a category of human-powered vehicles for handicapped riders, developed around wheelchair sports applications. Two styles have emerged: one is a variation on the conventional wheelchair, in which the rider pushes with the hands directly onto rings attached to the main wheels; and the other, typically referred to as a xe2x80x98handcyclexe2x80x99, derives from the bicycle, but with additional wheels, and the driving pedals moved to within reach of the hands. There are a number of disadvantages to both of these styles which render them unsuitable for either daily outdoor transportation, or for casual, recreational use, in the way that an able-bodied person might use an ordinary bicycle. Neither style is particularly well suited to the human form in terms of the ergonomic factors of efficient muscle use, strain avoidance, and overall rider comfort. By and large, they are adaptations of designs which have been optimized over time, for other purposes, or other muscle groups.
Most wheelchair-style designs force the rider to sit in a doubled-over position, head facing towards the ground, thereby restricting both breathing, vision and rider comfort. This style offers none of the mechanical advantages that bicycle-type gearing might deliver, but requires the rider to grip the wheel ring, push through an arc using an awkward extension of the wrist muscles, release the grip, retract the arm and reposition the hand for the next thrust; this sequence must be repeated constantly, and in rapid succession in order to gain forward momentum.
The typical handcycle positions the pedals, sprocket and chain uncomfortably close to the rider""s face, often directly in the line of sight. Such a layout also requires the rider to operate the vehicle with his arms in a constantly elevated position, with the consequent strain and fatigue that results from this attitude. The handcycle style presents a safety concern in the location of the handbrake levers: because the hand pedals require full 360 degree freedom of rotation around their axes, the brake levers typically are not attached to these same hand pedals, but are located on a frame member nearby, requiring the rider to release his grip on the thrust member and reposition it elsewhere for braking, which is far from optimum in emergency situations.
Both styles tend to be quite low-slung in order to achieve a degree of stability while cornering quickly. But this low seating position makes mounting and dismounting difficult, and makes these vehicles quite unsafe for street use, as the rider""s head is positioned lower than the fender height of the average automobile. As well as seriously restricting the rider""s field of vision, in traffic situations both rider and vehicle can fall below the line of sight of drivers nearby. Unable to either see or be seen, riders of such vehicles pose a considerable risk to their own wellbeing.
These factors, as well as the high cost of most commercially available sports wheelchairs and handcycles, are seen as impediments to their more widespread adoption and enjoyment by the handicapped community. The present invention attempts to solve the foregoing problems by configuring a design which is based on the premise that a maximum amount of sustained power can be extracted from the rider""s arms and upper torso working in unison, in a rowing action that powers on the forward as well as the backward stroke, wherein the seat is arranged in relation to the rowing handles so as to provide firm support against which to both push and pull, and wherein the rider is positioned in a semi-reclined and relaxed attitude, facing forward and suitably elevated, with the driving arms falling in a natural, comfortable and neutral position with regards to muscle extension. Many patents have been issued for designs, some quite extraordinary, which attempt to harness the rowing energy of the human body for the propulsion of a land vehicle. The common shortcoming of all such previously disclosed devices, which is resolved by the present invention, is the absence of a positive, safe, and mechanically simple method of steering the vehicle, which would allow the handicapped rider to lean into turns in an effortless and intuitive way.
A review of prior claims registered with the U.S. Patent Office revealed no fewer than 74 patents relating to human-powered devices incorporating a rowing or similarly reciprocal motion by which to impart motive power, of which the earliest appears to be U.S. Pat. No. 85,501 (Wood) in 1868. Nine patents were found in which an occupant propelled vehicle is steered by pivoting the seat about a generally vertical axis. A further 18 patents were identified which pertain to the steering of human-powered vehicles in which a leaning motion is either directly applied, or is the result of some other motion applied to initiate steering; this group is exclusive of the conventional bicycle inventions in which a leaning steering action is necessarily implied. (The full list of these prior patents is not cited here, but is attached for reference at the end of this submission as Appendix A). Many of these designs, as in the Wood patent, rely on the operator""s feet to perform some function, such as braking, steering, or in some cases, to assist in forward propulsion, while some patents apply to two-wheeled vehicles, which require use of the lower limbs for balance and stability.
U.S. Pat. No. 2,643,898 (Everest et al.) discloses the first instance of a wheelchair, in the familiar style most commonly in use today, propelled using a reciprocating drive; steering is achieved by independently powering wheels disposed on either side of the chair. A great many variants of this latter design have been disclosed, the most recent of which would appear to be U.S. Pat. No. 5,322,312 (Cammack), and most, if not all, of which steer in the same manner as the Everest instance.
The earliest apparent application of a reciprocal, hand-powered driving motion to a chair, which may be operated by a person without the use of his lower limbs, appears in U.S. Pat. No. 838,228 (Williams). Steering in the Williams instance is by way of a lever handle. U.S. Pat. No. 1,105,216 (Smith) describes the first vehicle which could be said to impart the spirit, if not the embodiment of the present invention, but employs two levers operating in opposition to one another, and steers by way of one of the levers which is linked to the front wheel.
U.S. Pat. No. 4,925,200 (Jones), and U.S. Pat. No. 5,209,506 (Klopfenstein) disclose rowing powered cycles utilizing a single centrally located lever to provide propulsion to the driven wheel, and a rotatable handlebar attached to this lever to provide steering. U.S. Pat. No. 4,460,190 (Spiess), U.S. Pat. No. 4,705,284 (Stout), U.S. Pat. No. 5,536,029 (Gramckow), disclose lever powered cycles wherein the steering is provided by a lateral motion of one or more of the lever handles. Each of the foregoing five mentioned patents requires complex, non-intuitive arm and wrist motions for steering, excessive wrist and forearm strength, or both.
U.S. Pat. No. 85,501 (Wood) is also the earliest claim which was found pertaining to the steering of a vehicle having at least three wheels, either by leaning the body of the occupant or the vehicle frame, or by inducing this leaning by the action of a steering wheel or other means. In this patent, as in subsequent and similar U.S. Pat. No. 252,455 (Giles), U.S. Pat. No. 3,958,814 (Smith), U.S. Pat. No. 4,132,435 (Wilson), U.S. Pat. No. 4,279,429 (Hopkins et al.), U.S. Pat. No. 4,432,561 (Feikema et al.), U.S. Pat. No. 4,469,344 (Coil), U.S. Pat. No. 4,740,004 (McMullen), U.S. Pat. No. 4,526,392 (Berkstresser), and U.S. Pat. No. 4,789,173 (Lofgren et al.), motive power is supplied by the riders legs, or some combination of arms and legs.
U.S. Pat. No. 329,755 (McIntosh) discloses a hand-pedaled tricycle wherein steering is achieved at the single front wheel, through a long and complex mechanism, driven by a lateral sliding of the rider""s seat back.
U.S. Pat. No. 5,354,084 (Lofgren et al) discloses a hand-powered vehicle, based on the inventor""s earlier disclosure, cited above, but employing in this instance a bicycle-style pedal crank located within reach of the rider""s hands. Both instances employ an articulated frame, hinged in the middle, which allows the rider to steer the vehicle by shifting is weight from side to side.
None of the foregoing patents employs a steering mechanism as disclosed in the present invention. One U.S. Pat. No. 5,028,064 (Johnson), does disclose a three-wheeled racing wheelchair which is steered by the movement of a laterally pivotable seat, similar to that disclosed in the present invention. The rider can lean into a corner, thereby tilting the seat, and thus affect steering. The preferred embodiment of the present invention differs from, and improves upon said Johnson invention in three significant ways:
1) the Johnson patent discloses in claim 1 a xe2x80x9cseat including a lowermost portion positioned below the axes of said large wheelsxe2x80x9d and a xe2x80x9cknee support means above the axes of the large wheelsxe2x80x9d, which arrangement is illustrated in FIG. 1 of the Johnson patent; the Johnson patent further discloses in claims 7 and 20 an optional xe2x80x9cbiasing means for urging said trailing wheel to a desired central position.xe2x80x9d A central principle of the present invention is that the seating position of the rider, with the legs generally below the torso, and with the rotational axis of the seat vertically disposed sufficiently above the seat bottom, places the greater proportion of the rider""s body mass below the seat axis, keeping the seat centered by the force of gravity, thereby maintaining straight line directional control; the Johnson disclosure neither claims nor illustrates this to be a factor in its design. The present invention also effectively resolves the centering problem without introducing any additional mechanical complexity.
2) In the Johnson invention, steering is affected by a single trailing wheel; the present invention steers two leading wheels, and employs a steering geometry, known as xe2x80x98Ackermanxe2x80x99, whereby the arcuate path described by the outer wheel in a turn is of a greater radius than the arcuate path of the inner wheel, which reduces tire scrub and improves turning efficiency.
3) In the Johnson invention, motive force is provided by the action of rotating the driving wheels directly by hand. The preferred embodiment of the present invention employs a hand-enabled reciprocating drive mechanism attached by a linking means to the rear wheel, permitting in a further embodiment the inclusion of variable gear ratios in said linking means, with the resultant mechanical advantage derived therefrom.
The present invention is a rider-propelled three-wheeled vehicle designed for, but not limited to, persons with disabilities of the lower limbs. The preferred embodiment of the present invention includes a frame, at least one driven rear wheel rotatably attached to the frame, two steerable front wheels rotatably attached to the frame, a seat pivotally mounted on a longitudinal and generally horizontal axis and a linking means connecting the seat to the front wheels. The vehicle can be steered by the inclination of the rider""s body side to side, so that rotation of the seat about its mounting axis imparts a displacement of the steering linkages, thus steering the front wheels. The seatmounting axis is vertically disposed sufficiently above the seat bottom, and the position of the rider""s body is so maintained, as to place the greater proportion of the mass of the rider below this axis, so that the force of gravity, acting upon the body of the occupant, maintains the occupant in a vertical orientation when no leaning force is applied, thus automatically centering the steering and maintaining straight line control.
In the preferred embodiment, the vehicle is propelled by the fore and aft movement of a pair of reciprocating handlebars, connected through a linkage to the driven wheel, in a simulated rowing motion, powering on the fore as well as the aft stroke. The rotation of these handlebars is constrained to a vertical plane parallel to the longitudinal axis of the vehicle, so that the rider may use these handlebars as a brace against which to control the amount of lean, and therefor control the vehicle direction.
The brake actuating levers are positioned conveniently on the handlebars, in the manner found on conventional bicycles. The mounting positions for the seat, footrest, brake lever, and drive ratio control are all adjustable so as to allow the vehicle to be used by persons of varying size and strength. One embodiment of the present invention includes a means of varying the drive ratio by way of a standard cycle derailleur, internal gearing, or other means.
One object of the present invention is to provide, for persons with disabilities of the lower limbs, a vehicle which is functionally equivalent to a bicycle in terms of utility, rider comfort, safety and enjoyment. A further object is to provide a vehicle which is specifically adapted to, and designed for, the limited muscle groups and movements available to persons with lower limb disabilities, and which is not merely an adaptation of a conventional wheelchair, or of designs optimized for persons with the full use of their legs. A further object is to describe a vehicle which represents the simplest possible design which can meet such ends, utilizing as much conventional and readily available hardware as practical in order to achieve the lowest possible cost, and thereby make the vehicle available to the widest possible market.